Citing your sources means telling where you got particular ideas or bits of information that did not originate in your own head; sometimes called giving credit, attributing, or referencing.
A References page (APA format) must be included with a research paper/project. Academic standards require all writers to acknowledge the authors whose work they use when preparing papers and reports. As you research, you should build on the work of previous writers and researchers. Whenever you draw on another's work, you must document your source by indicating what you borrowed--whether facts, opinions, quotations or information and ideas. You MUST indicate the source of the appropriated material so that readers do not mistake them for your own.
Citation or documentation is NOT needed when:
DEFINITION OF PLAGIARISM:
Derived from the Latin word plagiarius ("kidnapper"), to plagiarize means "to commit literary theft" and to "present as new and original an idea or product derived from an existing source (Merriam-Webster’s collegiate dictionary, 11th ed., 2003)
If you have any doubt, cite your sources to avoid committing plagiarism.